JPH0123900B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to an improvement in a method for manufacturing a sintered substrate for a storage battery. (Prior art) Conventionally, as a manufacturing method for sintered substrates for storage batteries, a slurry composition made by mixing 5% by weight or more of MC (methyl cellulose) as a thickener with nickel powder and kneading it with an appropriate amount of water is made into a porous material. The method used was to fill a core plate, apply it and mold it to a certain thickness, and then sinter it. However, this method has drawbacks such as a large number of bubbles being generated during kneading, making it difficult to obtain a sintered substrate with uniform microporosity, and the active material filled in the substrate falling out to a large extent. Therefore, in order to prevent the generation of bubbles during kneading, a method has been used in which a small amount of an antifoaming agent is added together with a thickener to prevent the generation of bubbles while forming and sintering. It can also be used as a thickener to be mixed with nickel powder.
A method is known in which CMC (carboxymethylcellulose) is used alone instead of MC. (Problem to be Solved by the Invention) However, in the above method, when an antifoaming agent is added together with the former thickener and molding and sintering is performed, the expansion rate becomes extremely high during formation due to the mixing of the antifoaming agent. A major problem was that the sintered substrate part would peel off or fall off, making it impossible to manufacture the electrode plate smoothly and without loss. In addition, in the case of the latter method, in which CMC is used alone as a thickener mixed with nickel powder, no foam is generated and there is no need to use an antifoaming agent, but the active material impregnation cycle does not require the use of MC. There was a problem that required twice or more times than the previous one. The present invention solves these problems and provides a sintered substrate for a storage battery that does not require the use of an antifoaming agent, reduces the expansion rate due to charge/discharge cycles during formation, and prevents the sintered plate active material from falling off. The purpose is to provide a manufacturing method. (Means for Solving the Problems) As a result of intensive study on a method for manufacturing a sintered substrate for storage batteries that achieves the above object, the present inventors found that conventional MC (methyl cellulose) was used as a thickener.
Knowledge that by blending CMC (carboxymethyl cellulose), it is possible to manufacture sintered substrates for storage batteries that do not require the use of antifoaming agents, have rapid impregnation with active materials, and have low swelling during chemical formation. I got it. The present invention has been made based on this knowledge, and is based on the above knowledge.
consisting of a mixture of CMC and MC, and CMC of MC
2 to 2 thickeners containing 70% by weight or less of
It is characterized by adding and mixing 4% by weight, kneading the mixture with water to form a slurry composition, and sintering the composition. MC relative to CMC in the thickener used in the present invention
The reason for making the amount of CMC less than 70% by weight is that
The use of MC has the effect of enlarging the pores and increasing the amount of active material attached, but if MC exceeds 70% by weight,
This is because the viscosity of the slurry composition obtained by mixing CMC into the metal powder particles for sintering decreases, and the sintered substrate created by sintering becomes brittle. In addition, CMC with a MC content of 70% or less by weight
The reason why the amount of the thickener made of the MC mixture added to the metal powder for sintering was set at 2 to 4% by weight is that if the amount of the thickener added is less than 1.5% by weight, the thickening effect will be poor. This is because if the amount of the thickener added is 4.5% by weight or more, it becomes necessary to use an antifoaming agent. (Example) Next, the present invention will be explained using a nickel sintered substrate for a nickel-cadmium storage battery electrode plate as an example. Further, the drawings show process diagrams of the manufacturing method of the present invention. A mixture of CMC and MC mixed as a thickener at a blending ratio of CMC=1.5:MC=1.0 in the "thickener blending step" is added at 2.5% by weight to 100 nickel metal powder particles. "Thickener addition and mixing step"'', kneaded with an appropriate amount of water, prepared this slurry composition in the ``composition forming step'', placed this slurry composition in a coating and filling container such as a hopper, and placed it in a large number of slurry filling containers. The slurry composition is passed through a metal core plate having holes, and the slurry composition is filled and coated on the metal core plate to form a slurry coating layer of a predetermined thickness on both surfaces thereof. This is then passed through a sintering furnace and subjected to the sintering process.
A nickel sintered substrate of the present invention was obtained. The thus obtained sintered substrate of the present invention was sequentially subjected to a nickel or cadmium active material impregnation treatment and a chemical conversion treatment in a conventional manner to obtain an electrode plate filled with a predetermined amount of active material. The results of the active material impregnation cycle (times) and the swelling rate (%) during chemical formation are shown in the following table. For comparison, a sintered substrate using MC alone as a thickener and a sintered substrate using CMC alone as a thickener were created, and each substrate was impregnated with active material in the same manner as the sintered substrate of the present invention. A chemical conversion treatment was performed to make an electrode plate. The results of the active material impregnation cycle (times) and the swelling rate (%) during chemical formation are shown in the following table.

[Table] As is clear from the table, the impregnation treatment cycle required to impregnate a predetermined amount of active material in the sintered substrate for storage battery obtained by the method of the present invention is as follows: Compared to the sintered substrate for storage batteries obtained by the method used in this method, the cycle time is approximately half that of the sintered substrate for storage batteries, and the swelling rate during charge and discharge cycles during formation is lower than that obtained by the method using MC alone as a thickener. It was significantly reduced compared to the obtained sintered substrate for storage battery. Therefore, the present invention can be used satisfactorily and stably, with significantly reduced drop-off of the active material and sintered substrate.
It was confirmed that it is possible to obtain a sintered substrate for storage batteries with an extended lifespan. (Effect of the invention) As described above, according to the present invention, the CMC of MC
Add and mix 2 to 4% by weight of a thickener consisting of 70% by weight or less with respect to the metal powder for sintering, knead this with water to form a slurry composition, and sinter this. Since the sintered substrates for storage batteries are manufactured using the same technology, there is no need to use antifoaming agents that cause problems when manufacturing electrode plates, and the impregnating effect of the active material can be quickly obtained, and the charging and discharging cycles can be improved. On the other hand, it has the advantage that it is possible to extremely easily produce a stable, high-quality electrode plate with a low swelling property and an increased service life.

[Brief explanation of drawings]

The drawings are process diagrams of the manufacturing method of the present invention.

Claims (1)

[Claims] 1 CMC and other metal powders for sintering such as nickel
consisting of a mixture of MC and 70 to CMC of MC.
2 to 4% by weight of thickener consisting of less than 2% by weight
1. A method for manufacturing a sintered substrate for a storage battery, which comprises adding and mixing, kneading the mixture with water to form a slurry composition, and sintering the composition.